Random Keyhole

[SkullyDogPDW]

This was with my DDM4–PDW at 50 yards… Using Berry’s, 220 grain bullets. 9.4 grains of N110 and a COAL of 2.240. Avg FPS was 1024. What the heck is going on with that one keyhole?

 

[SkullyDogPDW]

I forgot to mention it’s a 300 blackout.

 

[wkdickinson]

I know nothing about a 300 Blackout. But I would be very concerned about not only the "keyholed" round but also 3 "9s" at 50 yds. My guess is you have something seriously wrong, that you are only getting a glimpse of.

 

[Murray Brook]

All the other bullet holes look ok I would think. Maybe a bad bullet.

 

[mgunderson]

What is the barrel twis? 220s and subsonic will was a fast twist. You may want to try a shorter bullet. Just a thought.

 

[GetReal]

Heavy bullets need a fast twist bbl.

Also whats bbl length?

That keyhole along with that shotgun pattern at fifty yards suggest to me your barrel isn't stabilizing your bullets.

 

[GetReal]

Here:

 

[dellet]

The two marked holes are marginal. all the others are unstable. The keyhole has a very good chance of being a baffle strike. That’s not a random keyhole, every other shot on that target is a good clue it was coming.



Is the load compressed? Easy to damage a soft bullet that way. Lots of possibilities.

First things are to confirm twist rate by actually checking it, not reading markings and then check bullet diameter.

Need to add that a quick of Berry’s loading tips. They recommend 2.150”, are you absolutely sure it can be loaded to 2.240”.

They also warn against exceeding 1000 fps in a 1/5, you don’t happen to have one?

 

[jelenko]

Easy to say now, but I also saw a bunch of out of round shot holes. I was thinking the load/twist were marginal with one round less stabilized for whatever reason.

 

[Oso]

what Dellet said. Also check your suppressor mount. If suppressor or muzzle brake brake is loose then may result in baffle strikes and inconsistent shot pattern.

The rounds all look like they are coming in off-center from the right. This is either because target isn't perpendicular to shooter (angled / tilted back to left) or bullet flight is not stable.

The group size could be the rifle, ammo or the shooter. At 50 yards the group is large, but it is subsonic ammo. I have seen plenty of factory subsonic ammo shoot 2”-3” at 50 yards.

 

[6MMsteve]

they all look unstable, always use 90wt paper so your holes are perfect, then you can clearly see destabilized bullet holes, Wally World has the heavy paper it's good to use and easy to measure group size, and see how your bullets are impacting. I think

 

[GetReal]

they all look unstable, always use 90wt paper so your holes are perfect, then you can clearly see destabilized bullet holes, Wally World has the heavy paper it's good to use and easy to measure group size, and see how your bullets are impacting. I think

Agree. That Shoot-N- C stuff usually tears unevenly, too.

Im curious why so large a shot pattern at 50 yds. Offhand rapid fire, or bullet instability ?

 

[Fuj]

Just about all them bullets are going in cockeyed......If you are relying
on this firearm for self defense since it is a PDW, I'd leave it alone......LOL